放顶煤采场顶板运动规律的研究

RULES OF ROOF MOVEMENT IN SUB-LEVEL CAVING WORKINGS

利用离散元和有限元数值模拟及力学解析计算，分析了放顶煤采场中上覆岩层运动规律；认为采场上覆岩层运动为分层运动，运动结构为拱－梁结构；拱－梁转换的实现，是以拱顶的失稳升高为条件，在分析了影响顶板运动的主要因素（顶板岩层断裂角、放煤步距、顶板岩层块体尺寸、顶煤厚度）的基础上，认为放煤步距过大（≥２ｍ）会降低放煤率，增大老顶垮落的动压冲击程度。放顶煤工作面与非放顶煤工作面的区别是，采空区充填系数小，顶板岩层运动剧烈，走向方向超前支承应力峰值较大。

The rules of overlying rock in a sub-level caving face was studied by using DEM and FEM and mechanical analytical calculation. It is considered that the movement of overlying rocks is a separation movement. The moving structure is an arch-beam structure. The condition for arch and beam transformation is the increase of instability height of arch. After investigation of the main factors for roof movement, i. e. the fracture angle of roof, coal drawing interval, size of rock blocks, thickness of top coal, it is considered that when the coal drawing interval is equal to or greater than 2 m, the rate of coal drawing will decrease and the dynamic impact of main roof caving will increase. The differences between the coal drawing face and non-coal drawing face are low stowing factor in the goaf, vigorous movement of roof, and high stress peak abutment pressure along the strike.